I haven't weighed before and after, but ~400 grams of dry wheat/rye feed my duckies for 2 days. A 50lbs bag (22Kg) would make 55 bins, enough for 110 days.
Maybe i should just feed them more greens and safe on pellets. There's enough room in my garage for a second fodder tower…
I have 10 hens, and I give them half a bin of fodder per day. If I give them more, it is frozen solid before they eat it all.
My chickens are actively laying eggs, so I always have layer feed available to them 24/7 because the commercial feed also has calcium and other good stuff for their egg laying. If that was not a concern, I think maybe they could survive on just eating fodder, but I don't know for sure. I use my fodder as a supplement to their layer feed, and not as a substitute. But obviously I could save lots of money if they only ate fodder (a 50 pound, $7.25 bag of barley makes about 250 pounds of fodder).
The fodder tower I built is so cheap that I figured it paid for itself in the first couple of batches of fodder. If I had more birds and/or need for more fodder, I'd build a second tower, or more, in a heartbeat.